noun

• (countable) The act of calling into question or challenging the accuracy or propriety of something.
  "[…] Nevertheleſs there was no ſo much care, labour, ſtudy, and diligence employed on our Party, by them, our ſelf, and other, for attaining your Grace's Purpoſe, but there was as much done by others for the lett and empeachment of the ſame; […]"
• (countable) The act of calling into question or challenging the accuracy or propriety of something.
  "It is sometimes intimated that testimony which is direct and positive cannot legally be rebutted and overturned by presumptions less high than those which are juris et de jure in the absence of impeachment of the credibility of the witnesses. We are not prepared to accept that proposition unqualifiedly."
• (countable) The act of calling into question or challenging the accuracy or propriety of something.
  "He [William Howard, 1st Viscount Stafford] is charged in the Articles of Impeachment with Contriving the Death of the King, and being at ſeveral Meetings and Conſults about the King's Death, and Hiring Perſons to kill the King; And are theſe no Overt Acts? [...] My Lords, another Exception that is taken, is, That there is no Indictment. I conceive that an Impeachment of the Houſe of Commons is more than an Indictment. And there cannot be any doubt of that, the Impeachment of the Houſe of Commons having always been received and proceeded on by your Lordships."
• (countable) The act of calling into question or challenging the accuracy or propriety of something.
  "The Boſton Gazette of March 7 contains articles of impeachment of high crimes and miſdemeanors againſt Peter Oliver, Eſq; Chief Juſtice of the Superior Court of Judicature, &c., over the Province of Maſſachuſets Bay, by the Houſe of Repreſentatives in General Court aſſembled, [...] [T]he Aſſembly perſiſted in their impeachment, which was carried, upon a diviſion, yeas 92, nays 8: [...]"